The site for downloading Arduino seems to be out of order. I really want to take a look at Artduino, but I'm not confident about my skills to built from source - could anyone direct me to a tutorial on how to do it using xcode?

SVN, you mean? You only need the trunk/ folder:svn co svn://svn.berlios.de/arduino/trunk

This will put everything in a folder called "trunk" in your current directory. Feel free to rename it to something more meaningful, like "Arduino"; you'll still be able to build everything and update to newer version of the source.